In the prior art, a large-scale fixed type sun-shield umbrella has a central shaft which is fixed on a table surface or on ground. The central shaft may be a single-joint or multiple-joint product. There: is no rotation or tilting joint for adjusting the orientation of the umbrella. The expansion and folding of the umbrella are performed by rotating a manual stick, for example, that disclosed in U.S. Pat. No. 4,878,509, “Stepless Tilting Device For Umbrella”.
The defect of above said prior art is that the tilting angle of the umbrella is performed by adjusting a middle shaft of the umbrella by using two hands to shake an adjusting arm. The horizontal angle is adjusted by rotating the middle shaft. The operation needs more power and thus is inconvenient.
Next, the operation of expanding or folding an umbrella by shaking the adjusting arm is slow and not flexible. When the umbrella is inserted in the center of a table surface, the operation of the umbrella will be affected by the table surface. The user must lean forwards for operating the shaking arm so that the operation is not easy.